Acute lung injury is an event that occurs as a consequence of a variety of disease states which share a common pathobiological process, neutrophilic lung inflammation (NLI). NLI likely results from increased production of inflammatory cytokines and endothelial-leukocyte adhesion molecules, many of which are regulated by the ubiquitous transcription factor complex, NF-kappaB. Although NF-kappaB is necessary for directing high level transcription of many cytokines, adhesion molecules, and other pro-inflammatory genes in tissue culture, the extent to which NF-kappaB controls specific biological processes in vivo remains unanswered. Systemic inflammation induced by injection of bacterial lipopolysaccharide (LPS) results in a reproducible pattern of NF-kappaB activation in lung tissue, gene expression of several NF- kappaB-dependent cytokines, and NLI. At present, the proximate stimulus for NF-kappaB activation in the lung following LPS injection is unknown. NF-kappaB activation could occur as a result of direct stimulation of lung cells by LPS. Conversely, other mediators, such as TNFalpha or IL-1, could be primarily responsible for lung NF-kappaB activation in this setting. Another uncertainty is whether NF-kappaB is activated diffusely and simultaneously in all lung cells, or whether the timing and intensity of NF-kappaB activation differs among subpopulations of lung cells. The larger question concerns the extent to which NF-kappaB activation regulates production of cytokines and other pro-inflammatory molecules in vivo. It is uncertain whether NF-kappaB activation is merely a marker of significant acute inflammation. The following hypotheses are proposed to address these issues: 1) systemic LPS induces NF-kappaB activation in the lung through both direct stimulation of lung cells and action of the LPS-induced cytokines TNFalpha and IL-1,2) specific subsets of lung cells are differentially activated following LPS injection, and 3) targeting NF-kappaB in lung cells for molecular intervention will result in attenuation of LPS-induced neutrophilic lung inflammation. We have four specific aims to address these hypotheses using a murine model system of NLI following intraperitoneal injection of LPS. The first is to define the characteristic pattern of NF-kappaB activation in lung (compared to other organs) following intraperitoneal injection of LPS and relate NF-kappaB activation to expression of NF- kappaB dependent cytokine genes and NLI. The second specific aim is to investigate the specific cell types in the lung which respond to intraperitoneal LPS injection by activating NF-kappaB. The third specific aim is to modulate LPS-induced activation of NF-kappaB in the lungs by inhibiting the cytokine cascade or blocking IKappaB degradation. The last specific aim is to specifically target the NF- kappaB complex in the lung for molecular intervention using a trans- dominant inhibitor of the NF-kappaB complex. These studies should lead to a better understanding of the role of NF-kappaB in the molecular regulation of NLI, and may ultimately lead to better treatment strategies for the adult respiratory distress syndrome and other inflammatory lung diseases.